A computer network generally includes a number of network devices, such as switches, routers, and others, connected so as to allow communication among the devices and end station devices such as desktop machines, servers, hosts, printers, fax machines, and others. Each network device has a processor and a memory. Status variables and other values in the memory are continuously changed and updated as the device operates.
Computer networks have become ubiquitous in the home, office and industrial environment. As computer networks have grown ever more complex, automated mechanisms for organizing and managing the networks have emerged. These mechanisms are generally implemented in the form of one or more computer programs, and are generically known as network management systems or applications. Network management refers to the function of requesting and monitoring information on a network device relating to fault, configuration, status, performance and security. To monitor the status of a device in the network, a network management station or system transmits a message requesting information over the network to a software program or agent running on the target network device. In response, the agent sends a message over the network to the network management station. The communications are carried out according to an agreed-upon protocol, such as the Simple Network Management Protocol (SNMP).
However, the hardware and software that perform network management functions must often deal with many different network devices that communicate using device-specific protocols. Thus, the scalability of a network management system can be limited when new devices are added to the network with protocols that are not supported by the system. Also, network management systems can only return information about the current status of a device at the time the information is requested, in essence forming a “snapshot” of the status of the device. Finally, current network management systems lack the capability to analyze and monitor the information that is collected from network devices.
One past approach is to use network management data models and information bases in an attempt to normalize the desired information. Examples of such models include the Cisco Information Model, as implemented in the Asynchronous Network Interface element of certain network management systems from Cisco Systems, Inc. as well as other proprietary systems. These systems are capable of identifying devices in a network and gathering data from a device.
However, these approaches have numerous disadvantages. First, they are difficult to scale when changes occur, usually requiring a software upgrade, and cannot model all the information desired to do network management. Occasionally, committee reviews are required to approve the changes. Second, a network device may require separate network management software in order to accommodate the many different network communication protocols used to extract information from the device when it is not present in the network management models or databases. Third, models can only show the state of the network device at the moment the status is requested, and cannot generate information as to the performance of a device over time. This “snapshot” information is less meaningful to a user than is data that shows a trend between two or more data points in time. Finally, these models cannot generate a notification to a user when data falls outside a desired value or range of values.
Based on the foregoing, there is a clear need for a method of network management that can specify what device data to collect, where to collect it, when to collect it and how to analyze it after collection, without the need to upgrade the network management software. Also, there is a need for a method that is scalable with various network devices using different network communication protocols and can monitor network device activity.
The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.